Referring to FIG. 1, as is generally known in the art, an intravenous injection system for directly injecting medicine into a vein includes a bottle 10 containing Ringer's solution 11, a dripper 20 composed of an insertion needle 21 which is inserted through a closure lid provided to the bottle 10 and allows the Ringer's solution 11 to flow therethrough and a drip chamber 22 which is formed to allow the Ringer's solution 11 to drop in the shape of a drip 23 therein, an injection needle 50 to be inserted into the vein, a tube 40 connecting the dripper 20 and the injection needle 50 with each other and allowing the Ringer's solution 11 to flow therethrough, and an adjustment clamp 30 fitted around the intermediate portion of the injection tube 40 to allow the flow rate of the Ringer's solution 11 to be adjusted.
In an intravenous injection method using the intravenous injection system constructed as mentioned above, by fixedly placing the bottle 10 higher than the injection needle 50, the Ringer's solution 11 can be naturally injected into the vein due to the gravity of the Ringer's solution. In a procedure for adjusting the flow rate of the Ringer's solution 11, the drop cycle of the drip 23 can be changed as a user manipulates the adjustment clamp 30. In the adjustment procedure, a predetermined number of drips 23 are counted with the naked eye, and an elapsed time is checked by using a watch. Usually, as a doctor writes on a chart the number of drips 23 per minute and transfers the chart to a nurse, the nurse can adjust the dropping speed of the drip 23 by manipulating the adjustment clamp 30.
However, in this procedure for adjusting the flow rate of the Ringer's solution, since the procedure is implemented depending upon the user's eyes based on experience, it is difficult to precisely adjust the flow rate of Ringer's solution. In general, Ringer's solution must be injected by determining a flow rate in consideration of a patient's age, body and condition, the kind and the volume of Ringer's solution, and so forth. In this regard, because the adjustment procedure cannot precisely adjust the flow rate of Ringer's solution, a medical accident is likely to occur.
Therefore, it is necessary to quantitatively measure the flow rate of Ringer's solution so that the adjustment clamp 30 can be appropriately manipulated. In this regard, prior arts are disclosed in Korean Unexamined Patent Publication No. 2004-0048889 entitled “Volumetric flow measurement device for intravenous injection set” and Korean Unexamined Patent Publication No. 2005-0039780 entitled “A system for measuring the flow rate of Ringer's solution using a method of image signal processing.” Nevertheless, in these prior arts, since a drip in a drip chamber is sensed using infrared rays and the number of drips and the quantitative amount of Ringer's solution are determined, a precision can be deteriorated due to the influence by outside light, and when installing the device or system for measuring the flow rate of Ringer's solution, inconvenience is caused and a substantial cost is required. Due to these facts, the device or system could not be actually employed on a commercial scale.
Also, there has been disclosed Korean Utility Model Registration No. 20-0336940 entitled “Automatic detecting and pre-warning system for medicine instiller.” This system has a drop carrier which moves each time a drip drips in a drip chamber so that the flow rate of Ringer's solution can be measured from the outside. Nonetheless, this system suffers from defects in that the structure of a drip chamber should be changed and the system cannot be practically used due to the complexity of the drip chamber and the system.
Further, because the prior arts basically adopt a process of measuring a volume by a sensor, they cannot help but adjust the flow rate of Ringer's solution by entirely relying on the operation of the measurement device or system. In this connection, since it is difficult to properly handle a situation where the measurement device or system misoperates, demand exists for a measurement device which can be conveniently used by a doctor in charge or a person in charge of nursing and is free from troubles.
That is to say, because the measurement device or systems according to the prior arts cannot be practically used due to the problems described above, it is the norm in a hospital or a doctor's office for a nurse to measure the time during which a predetermined number of drips drip, using a watch having a second hand, and to calculate the flow rate of Ringer's solution. In this procedure, since it is necessary to alternately look at the watch and a drip chamber, an error is likely to be caused in the calculated flow rate. Hence, demands exist for a device for measuring the flow rate of Ringer's solution, which can be conveniently used, even by an unskilled person in charge of nursing.